This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Determine if estrogen advances and enhances the amplitude and synchrony of components of the circadian system whereas progesterone antagonizes these effects. To investigate whether the effect of estrogen and progesterone on mood sleep and behavior in postmenopausal women may be mediated by effects of the circadian system.